It’s not just the size of the sea ice that has changed, it’s also its character. Arctic sea ice has gotten dramatically younger. As NOAA explains, when it comes to ice, age refers to thickness and durability. Young ice is thinner and melts earlier in the summer. Older ice – which is typically four years or more – is ice that lasts year round and gets thicker over time. According to the National Snow and Ice Data Centerold ice can get between six and eight feet thick.
As you can see in the image, older Arctic ice is a piece of what it once was. In 1985, 33% of the Arctic ice was very old ice; in March 2020, only 4.4% of the sea ice was old.
According to NOAA20 to 30 years ago, the sea ice in the Arctic was dominated by ancient sea ice. Over time, however, old ice drifted from the Arctic through the Fram Strait, where it melted in the relatively warmer waters of the Atlantic Ocean. This wasn’t a problem at the time as new batches of old ice were created in the Beaufort Gyre, which NOAA describes as a “nursery” for young ice to grow thicker and stronger as it floats around for years. Today, summers in the southern branch of the Beaufort Gyre are often too hot for ice to survive, the agency said.
To make a sentence from the NSIDC, this “Benjamin Button Ice” is an element in a dangerous cycle, one in which rising air and ocean temperatures more readily destroy freshman ice and weaken older ice. If this cycle continues and older ice disappears from the Arctic Ocean, the world could see ice-free summers in the Arctic as early as 2030.